Double-walled solar heater apparatus and method for use

ABSTRACT

The solar heater apparatus disclosed comprises an inner container and an outer container each having an opening forming a mouth. The inner container is contained within the outer container and has on its outside surface a solar-selective coating optimized to absorb a large fraction of the incident solar radiation while reradiating little of the absorbed energy. The two containers are joined creating one unified apparatus with a reservoir, an opening and a void between the two containers. The void is evacuated to reduce the heat loss due to thermal conduction from the inner container and the contents of the reservoir. In operation, the reservoir is filled with material and exposed to the sun. The solar radiation from the sun penetrates the outer container and is absorbed by the solar-selective coating and, by conduction, passes thermal energy through the inner container into the apparatus reservoir heating the reservoir contents.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 60/845,697 filed on Sep. 19, 2006 and all of saidapplication is herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT:

Not Applicable.

NAMES OF PARTIES TO JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTINGCOMPACT DISC APPENDIX

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to techniques for heating materials using a solarheat apparatus. In one embodiment, the invention relates a solar heatapparatus for heating liquids, such as water, for disinfecting andcooking purposes.

2. Description of the Prior Art

The need for safe drinking water covers the entire world's population.Non-portable drinking water is a major problem for much of the world'spopulation.

Chlorine is considered a well known technique for disinfecting drinkingwater. However, chlorine is a toxin that must constantly be replenishedin order to be effective. As a replenishable chemical, there is always acontinuing cost incurred. And certain logistical situations makedelivery of such chemicals difficult.

The lack of fuel for cooking is a very serious problem in many parts ofthe developing world. Large numbers of people are forced to walk manyhours every day to gather sufficient firewood to cook their daily meal.

Other techniques of disinfection such as membranes, resin beds, and thelike, require electricity for operation. This source of energy may notbe available at the site or would be expensive when compared to othermethods.

Heat is a very effective method of disinfecting drinking water. However,the lack of fuel in certain locations can limit the application of fuelbased heating methods to disinfect water or heat water for cooking.

Contrary to popular opinion, boiling water for many minutes or evenhours is not necessary to successfully disinfect. Numerousinvestigations have been conducted to demonstrate that temperatures muchlower than the sea level boiling point (100 C) can successfullydisinfect drinking water. Heat inactivation of microorganisms isexponential with time. In general, disinfection times can range frominstantaneous at 90 C to 20 minutes at 55 C.

Applying solar energy to heat liquids is known in the prior art. Butmany implementations, such as flat-plate collectors or parabolic troughsystems, are inefficient. Some evacuated-tube collectors can achievehigh temperatures (170° F. to 350° F.), temperatures high enough todisinfect water. However, many of these evacuated-tube collectors aremore expensive than other implementations, with glass-to-metal seals andunit area costs about twice that of flat-plate collectors.

All-glass evacuated-tube designs are now available which address some ofthe efficiency issues with prior designs. These “dewar” design tubesfeature a vacuum contained between two concentric glass tubes, with thesolar-selective coating on the outside surface of the inside tube. Thereare no glass-to-metal seals in this implementation. This type ofevacuated tube has the potential to become cost-competitive with priorsolar collector designs.

In conjunction with the physical structure of new solar collectors, thesolar-selective coating provides improvements to the prior art. An idealsolar-selective coating is a very efficient absorber of light of thewavelengths of the solar radiation spectrum, while simultaneously beinga very poor radiator of wavelengths in the spectral range of bodies attemperatures of 100-300 deg. C. Solar coating development now includesdouble cermet layer structure for solar-selective coatings which have avery high photo-thermal conversion efficiency. And recent researchachievements have allowed the double cermet solar-selective coatings tobe economically manufactured. Other solar selective coatings which areapplicable to this invention include but are not limited to blacknickel, black chrome, and other nanostructured materials.

These advances in solar collector design and solar coatings are creatingopportunities for improved implementations of solar-powered heating.Applications related to water heating for houses, industrial facilities,pools and similar applications are incorporating these improvements.However, small, personally portable methods to harness solar power forheating materials, cooking and disinfecting water are not readilyavailable.

Thus, the need exists for an economical and portable technique forheating materials with solar energy for purposes such as cooking ordisinfecting drinking water.

BRIEF SUMMARY OF THE INVENTION

To address the shortcoming of the prior art, this invention combines thetechnology advancements used for solar heating and applies them to a newapparatus to heat materials such as water in a portable and economicallyefficient manner.

Advances in solar collector design and manufacture enable more efficientsolar collector designs. Advances in solar coatings now include cermetsolar-selective coatings which have a very high photo-thermal conversionefficiency and very low energy losses due to reradiation. Advances inmanufacturing allow these coatings to be applied in an economical way.The costs of high-temperature solar collectors manufactured by these newmanufacturing methods make collectors using cermet layers much moreeconomically appealing than other solar collectors.

The new apparatus disclosed, a solar heater apparatus, comprises aninner container and an outer container each having an opening forming amouth. The inner container is smaller than and contained within theouter container. The two containers are joined at the mouth of eachcreating one unified container with an internal reservoir, an openingand a void between the two containers. The gas in the void is removed tocreate a vacuum that helps reduce thermal conductance loss.

Although similar, this design deviates from past dewar flaskimplementations. The outer container of the apparatus is transparentallowing solar radiation to be passed through the void and on to theinner container. The outside surface of the inner container is coatedwith a solar-selective coating which absorbs solar radiation andconverts that radiation to thermal energy. The thermal energy is passedby conduction through the inner container and to the contents of theinner container. In one implementation, using a double cermet layerstructure as the inner container coating enables the inner container toefficiently achieve temperatures sufficient to disenfect or sterilizewater in the apparatus.

This apparatus design provides a portable apparatus wherein non-sterilewater can be put into the apparatus, the apparatus can be set into thesun and solar radiation can heat the water to a temperature sufficientto disinfect or sterilize the water in the apparatus.

It is an object of this invention to provide a solar heater apparatusfor heating a material comprising an outer container transparent tosolar radiation with a mouth, an inner container with a mouth and anouter surface having a solar selective coating, the inner container iscontained within the outer container and both containers are joined attheir mouths creating an apparatus opening, an apparatus reservoir, anda void between said outer and inner container.

It is another object of this invention to provide a solar heaterapparatus as described above wherein the solar selective coatingcomprises a coating capable of simultaneously converting to heat atleast about 85% of said solar radiation while reradiating less than 15%of the heat while the reservoir temperature is at a temperature of lessthan 100° C.

It is a further object of this invention to provide a solar heaterapparatus as described above wherein the solar selective coatingcomprises at least one cermet layer.

It is another object of this invention to provide a solar heaterapparatus as described above wherein the outer container and the innercontainer form a self-supporting apparatus whereby the apparatus can beplaced on a surface and exposed to solar radiation to transfer heat tothe apparatus reservoir.

It is an object of the invention is to provide a method of heatingmaterial comprising the steps of providing a solar heater apparatuscomprising: an outer container, transparent to solar radiation, having amouth; an inner container having a mouth and an outer surface having asolar collective coating to absorb solar radiation; the inner containercontained within the outer container and both containers joined at theirmouths creating an apparatus opening, a apparatus reservoir, and a voidbetween said outer and inner container; and inserting a material intosaid apparatus reservoir, subjecting said apparatus to solar radiationheating said material and removing said material from said apparatusreservoir.

Another objective of the present invention is to provide a non-chemicalapparatus and method for heating materials such as water.

Another object of this invention is to provide a non-toxic apparatus andmethod for heating materials such as water.

Another object of this invention is to provide a simple apparatus andmethod for heating materials such as water.

Another object of this invention is to provide an efficient apparatusand method for heating materials such as water.

Another object of this invention is to provide a reliable apparatus andmethod for heating materials such as water.

Yet another object of this invention is to provide an easy-to-operateapparatus and method for heating materials such as water.

Yet another object of this invention is to provide a self-containedapparatus and method for heating materials such as water.

Yet another object of this invention is to provide an apparatus andmethod requiring no fossil fuels or electricity for heating materialssuch as water.

Yet another object of this invention is to provide a portable apparatusand method for heating materials such as water.

These together with other objects of the invention, along with thevarious features of novelty which characterize the invention, arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and the specific objects attained by its uses,reference should be had to the accompanying drawings and descriptivematter in which there are illustrated embodiments of the invention. Theforegoing has outlined some of the more pertinent objects of thisinvention. These objects should be construed to be merely illustrativeof some of the more prominent features and applications of the presentinvention. Many other beneficial results can be attained by applying thedisclosed invention in a different manner or by modifying the inventionwithin the scope of the disclosure. Accordingly, other objects and afuller understanding of the invention may be had by referring to thesummary of the invention and the detailed description of the preferredembodiment in addition to the scope of the invention defined by theclaims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1A shows a perspective view of one embodiment of the solar heaterapparatus.

FIG. 1B shows a top view of one embodiment of the solar heater apparatusmarked for cross-section A-A.

FIG. 2 shows a cross-sectional side view of the embodiment of theinvention along section A-A of FIG. 1B.

FIG. 3 shows cross-sectional side view of an alternative embodiment ofthe invention.

FIG. 4 shows a partial cross-sectional view, defined between section B-Band C-C of FIG. 2 of the solar heater apparatus.

FIG. 5 shows a cross-sectional side view of one embodiment of the solarheater apparatus interacting with solar radiation.

FIG. 6 shows one embodiment of the method of heating material with thesolar heater apparatus.

DETAILED DESCRIPTION OF THE INVENTION

Before explaining the disclosed embodiment of the present invention indetail it is to be understood that the invention is not limited in itsapplication to the details of the particular arrangement shown since theinvention is capable of other embodiments. Also, the terminology usedherein is for the purpose of description and not of limitation.

The Solar Heater Apparatus:

FIG. 1 shows a perspective view of one embodiment of the solar heaterapparatus 10. The general shape of this solar heater apparatusembodiment is a spherical flask. This apparatus has an apparatus opening33 and a base 12 to help serve as a self-supporting structure tostabilize the apparatus when it is resting on a surface.

FIG. 1B shows a top view of the solar heater apparatus 10 marked forcross-section A-A that is used in FIG. 2 and FIG. 4.

FIG. 2 shows a cross-sectional view of the solar collector apparatus 10comprising a flask shaped inner container 21 and a similarly flaskshaped outer container 11 each having an opening forming a mouth, 25 and13 respectively. The inner container 21 is smaller than and containedwithin the outer container 11. The two containers are joined (at theirrespective mouths) creating an apparatus opening 33 and a void 30between the two containers. The apparatus opening 33 provides access toan apparatus reservoir 34. The air in the void is removed to create avacuum. This vacuum helps reduce the conductive and convective heatloss. The flask shape of the apparatus helps make it a self-supportingdevice as well as increase the portability and durability of theapparatus over conventional solar vacuum tubes.

The inner container 21 is coated on its outside surface 22 with asolar-selective coating 24 which absorbs solar radiation and convertsthat radiation to thermal energy. The thermal energy is transferred byconduction to the inner surface 23 of the inner container 21, heatingthe contents of the apparatus reservoir 34. Solar radiation comprisesradiation from the sun.

One embodiment of the apparatus comprises both containers being made ofglass transparent to solar radiation. Examples of suitable glassmaterials for the containers include, but are not limited toborosilicate glass, offered for sale by Corning Incorporated of CorningN.Y. under the Pyrex trade name as well as glass offered for sale byother companies under other trade names. In this embodiment, the innerand outer containers are joined by standard glassworking methods and thevacuum is created by standard glassworking and vacuum processingmethods.

Another embodiment of the apparatus 10 includes the inner and outercontainers being made of other materials that are able to maintain avacuum, withstand high temperatures and provide a sufficient method toconnect both containers at their mouths. The outer container 11 can bemade from other transparent materials such as but not limited toplastics or transparent crystalline materials. The outer container 11can also be made from of a combination of transparent material andnon-transparent material as long as there is sufficient transparentmaterial to allow solar radiation to pass to the inner container 21.Other embodiments of the invention include the inner container 21 beingmade from transparent or non-transparent materials such as, but notlimited to metal with a solar-selective coating, which constructionwould make the apparatus 10 more rugged.

Another embodiment of the apparatus 10 includes the use of methods tojoin the inner and outer containers at their mouths through adhesive orsealing materials such as, but not limited to solder or epoxy that canwithstand high temperatures and maintain a vacuum.

FIG. 4 shows a partial cross-sectional view of the inner container 21 ofthe solar collection apparatus 10 shown in FIG. 2 between sections B-Band C-C. The outside surface 22 of the inner container 21 is coated witha solar-selective coating 24 which absorbs solar radiation and convertsthat radiation to thermal energy. The embodiment of the apparatus 10shown in FIG. 4 shows a double cermet layer structure as the innercontainer solar-selective coating 24. This coating helps the innercontainer 21 achieve sufficient temperatures to heat materials in theapparatus 10 for particular purposes, such as the temperature sufficientto disinfect or sterilize water. In this embodiment, the double cermetsolar-selective coating 24 is made of multiple layers of material. Afirst layer against the outside surface 22 of the inner container 21 isa metal infrared-reflecting layer 25; a second layer is an absorbinglayer composed of two homogeneous cermet sub-layers, the first sub-layer26 near the metal infrared layer has a high metal volume fraction (HMVF)and the second sub-layer 27 has low metal volume fraction (LMVF); and athird anti-reflection layer 28 is composed of a transparent dielectricmaterial.

In double or other cermet layer solar-selective coatings 24, radiationof wavelengths typical of solar radiation is absorbed by the coatingwhich has very low reflectivity in this range of wavelengths, whileradiation of wavelengths typical of materials at a temperature in therange of 100-300 degrees C. is not radiated due to the coating's veryhigh reflectivity in this range of wavelengths. Radiation of convertedheat from the solar selective coating is also defined as reradiating.

Advances in manufacturing allow these coatings to be applied in aneconomical way. As an example, and not as a limitation, one method ofmanufacture includes a two-target dc magnetron sputtering technologyenables metal-aluminum nitride (M-AlN) and metal-aluminum oxide(M-Al₂O₃) solar-selective coatings to be economically applied to solarcollectors.

Embodiments of solar selective coatings include, but are not limited tothose capable of near simultaneously converting to heat at least about85% of said solar radiation while reradiating less than 15% of said heatwhile said coating temperature is at a temperature of less than 100° C.These conversion and reradiation values become less efficient as thetemperature of the apparatus and the coating increases. Examples of somespecific solar selective coatings include, but are not limited to blacknickel, black chrome, dark paint, other nanostructured materials andthose embodiments described by U.S. Pat. No. 5,523,132 and U.S. Pat. No.6,632,542 both of which are incorporated by reference.

Although FIG. 1 and FIG. 2 illustrate a spherical shape, other shapedcontainers are anticipated. For example, another embodiment of theapparatus is shown in FIG. 3. In this embodiment, the inner and outercontainers are of the form of cylindrical, straight-sided vesselsforming a shape similar to a pot or cup. The apparatus comprises theouter container 11, and inner container 21 with the solar-selectivecoating 24 applied to the outer surface 22 of the inner container 21.Although not required in other embodiments, in this embodiment, a hollowtransparent plug 40 is provided and shaped to be removably fitted intothe apparatus opening. The plug can be made from material similar to thecontainer of the apparatus. The void 41 within the hollow plug can beevacuated and a solar-selective coating 44 can be applied to the insidesurface 42 of the bottom portion of the plug 40. The solar-selectivecoating 44 performs the same purpose and therefore can be selected fromthe same type of coating as is suitable for the inner container 21coating. Although not required, to seal the plug 40 into the apparatusopening, an elastic retaining ring 45 can be mounted on the plug tocreate a seal between the plug and the apparatus. A handle 43 can beincorporated into the plug 40 to provide a means to remove the plug fromthe apparatus and allow access to the apparatus reservoir 34.

Another embodiment of the invention includes adding support elements inthe void between the inner and outer containers to support the innercontainer and make the assembly more portable and durable.

Another embodiment of the invention includes adding a rigid support forthe apparatus which supports the apparatus over or near an appropriatelyshaped reflective surface to increase the intensity of the sunlight thatstrikes the apparatus.

Another embodiment of the apparatus includes mounting the apparatus inproximity to a solar reflective surface so that sunlight and solarradiation which strikes the reflective surface is reflected onto theapparatus, thereby increasing the incident solar radiation and thereforethe energy absorbed by the apparatus in a given time.

Self-supporting shapes are convenient for some embodiments of theapparatus because they allow the apparatus to be more self-containedallowing it to be placed in solar radiation without the need foradditional equipment. However, it is anticipated that containers andholders may also be provided that can assist in positioning theapparatus to continue to be subjected to solar radiation while alsoholding the contents of the material in the apparatus reservoir.

Another embodiment of the apparatus includes adding material to theouter container to make the apparatus self-supporting or help protectthe apparatus from breakage when being used or moved. Rigid frames, orcaging can be used to encase the outer container yet still allow enoughtransparent area for solar radiation to interact with the innercontainer. An embodiment may also include a rigid baseplate to protectthe base of the outer container.

Solar Heater Apparatus in Operation:

The following operational description uses the solar heater embodimentas shown in FIG. 1 and FIG. 2 for illustration purposes and not forlimitation.

FIG. 6 illustrates one method of using the solar heater apparatus 10. Asshown in FIG. 6, the method starts with step 600 and is followed by Step610 of providing a solar heater apparatus 10 comprising an outercontainer 11 transparent to solar radiation having a mouth 13, an innercontainer 21 having a mouth 25 and an outer surface 22 having a solarselective coating 24 and the inner container 21 is contained within theouter container 11. Both containers are joined at their mouths creatingan apparatus opening 33, an apparatus reservoir 34, and a void 30between said outer and inner container.

Step 620 comprises inserting a material 35 such as water into theapparatus reservoir 34. The material 35 is put in and held within, orotherwise retained in the apparatus reservoir 34.

Other materials 35 that can be inserted into the apparatus reservoir 34include, but are not limited to waxes, plastics, surgical devices,cooking utensils, edible items, food and other materials that can beaffected by heat.

Step 630 comprises exposing the solar heater apparatus 10 to solarradiation. As illustrated in FIG. 5, in this step, the incident solarradiation 50, defined as that solar radiation that falls on or strikesthe apparatus 10, is absorbed by the solar-selective coating 24 andconverted to and passed by conduction as heat through the innercontainer 21 into the apparatus reservoir 34, thereby raising thetemperature of the content of the apparatus 10. In this embodiment, theapparatus 10 is exposed to the sun. The solar radiation from the sunpenetrates both the outer container 11 and the void 30 between the outerand the inner container. The solar radiation is absorbed by thesolar-selective coating 24 and converted to and passed through the innercontainer 21 into the apparatus reservoir 34 heating the water. Thevacuum created in void 30 reduces the conductive and convective heatloss from the inner container 21 and the content of the apparatusreservoir 34. As described earlier, the solar-selective coating 24reduces the reradiation, or radiation of converted heat, from the innercontainer 21. Although not required, an insulating plug 36 reduces heatloss from the apparatus reservoir 34 due to convection, conduction andevaporation from the contents of the apparatus 10. Thus, the apparatus10 allows the water temperature to heat, or rise relative to thesurrounding ambient temperature, for a sufficient period of time, todisinfect or sterilize the water or heat it for other purposes such ascooking. Temperatures sufficient to disinfect water include temperaturesof about 50° C. and above.

Step 640 comprises removing the material 35 from the solar heaterapparatus reservoir 34 for use.

The method is finished with Step 650.

Although this apparatus is not limited to functioning with water, theuse of the apparatus to disinfect water is illustrative of theefficiencies achieved with this solar heater apparatus. The temperaturesufficient for the disinfecting of water is a function of the watertemperature in the apparatus reservoir. The temperature of the apparatusreservoir is related to the solar radiation the apparatus is exposed to,the time of the exposure and the efficiency of the apparatus inabsorbing and retaining that radiation. Analysis of one embodiment ofthis apparatus shows that it is possible to achieve sufficienttemperatures to disinfect water more efficiently than other devices inthe art. Efficient embodiments such as this are helpful for situationswith low levels of solar radiation or situations where speed ofdisinfection is important.

While methods have been described as being used for sterilizing water,other embodiments of this method have other useful applications such asheating liquids, food or any other materials that can be put into theapparatus reservoir 34 for various purposes, including but not limitedto cooking, medical applications, process heat or other uses.

While the apparatus and methods have been described, disclosed,illustrated and shown in various terms of certain embodiments ormodifications which it has presumed in practice, the scope of theinvention is not intended to be, nor should it be deemed to be, limitedthereby and such other modifications or embodiments as may be suggestedby the teachings herein are particularly reserved especially as theyfall within the breadth and scope of the claims here appended.

With respect to the above description then, it is to be realized thatthe optimum dimensional relationships for the parts of the invention, toinclude variations in size, materials, shape, form, function and mannerof operation, assembly and use, are deemed readily apparent and obviousto one skilled in the art, and all equivalent relationships to thoseillustrated in the drawings and described in the specification areintended to be encompassed by the present invention.

Therefore, the foregoing is considered as illustrative only of theprinciples of the invention. Further, since numerous modifications andchanges will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact construction and operationshown and described, and accordingly, all suitable modifications andequivalents may be resorted to, falling within the scope of theinvention. Although this invention has been described in the above formswith a certain degree of particularity, it is understood that thepresent disclosure has been made only by way of example and numerouschanges in the details of construction and combination and arrangementof parts may be resorted to without departing from the spirit and scopeof the invention.

1. A solar heater apparatus for heating material comprising: an outercontainer, transparent to solar radiation, having a mouth; an innercontainer having a mouth and an outer surface having a solar selectivecoating to absorb solar radiation; and said inner container containedwithin said outer container and both containers joined at their mouthscreating an apparatus opening, an apparatus reservoir, and a voidbetween said outer and inner container.
 2. The apparatus in claim 1wherein said solar selective coating comprises a coating capable of nearsimultaneously converting to heat at least about 85% of said solarradiation while reradiating less than about 15% of said heat while saidcoating is at a temperature of less than about 100° C.
 3. The apparatusin claim 1 wherein said solar selective coating comprises at least onecermet layer.
 4. The apparatus in claim 1 wherein said outer containerand said inner container form a self-supporting apparatus whereby saidapparatus can be placed on a surface and exposed to solar radiation totransfer heat to said apparatus reservoir.
 5. The apparatus in claim 1wherein said outer container and said inner container are flask shapedwhereby said apparatus can be placed on a surface and exposed to solarradiation to transfer heat to said apparatus reservoir.
 6. The apparatusin claim 1 further comprising: a plug shaped to fit in said apparatusopening; said plus comprising a transparent hollow evacuated cylinderhaving a bottom portion, an inside surface and a solar selective coatingon said inside surface of said bottom portion; and said outer containerand said inner container are pot shaped whereby said apparatus can beplaced on a surface and exposed to solar radiation to transfer heat tosaid apparatus reservoir.
 7. The apparatus in claim 4 wherein saidapparatus is capable of near simultaneously converting to heat at leastabout 85% of said solar radiation while reradiating less than about 15%of said heat while said coating is at a temperature of less than about100° C.
 8. The apparatus in claim 4 wherein said solar selective coatingcomprises at least one cermet layer.
 9. The apparatus in claim 4 whereinsaid reservoir is capable of holding water and said solar selectivecoating comprises at least one cermet layer capable of transferring heatto raise the temperature of said water to a temperature at or above atemperature sufficient to disinfect water.
 10. The apparatus in claim 4wherein said reservoir is capable of holding a material and said solarselective coating comprises at least one cermet layer capable oftransferring heat to raise the temperature of said material to atemperature above an ambient temperature.
 11. The apparatus in claim 4wherein said reservoir is capable of holding an edible material and saidsolar selective coating comprises at least one cermet layer capable oftransferring heat to raise the temperature of said edible material. 12.The apparatus in claim 4 further comprising a solar reflective surfacewherein said inner container is placed in proximity to said reflectivesurface whereby said solar radiation incident to said apparatus isincreased.
 13. A method of heating material comprising the steps of:providing a solar heater apparatus comprising: an outer container,transparent to solar radiation, having a mouth; an inner containerhaving a mouth and an outer surface having a solar collective coating toabsorb solar radiation; said inner container contained within said outercontainer and both containers joined at their mouths creating anapparatus opening, a apparatus reservoir, and a void between said outerand inner container; and inserting a material into said apparatusreservoir; exposing said apparatus to solar radiation heating saidmaterial; and removing said material from said apparatus reservoir. 14.The method of claim 13 wherein said solar selective coating comprises acoating capable of near simultaneously converting to heat at least about85% of said solar radiation while reradiating less than about 15% ofsaid heat while said coating is at a temperature of less than about 100°C.
 15. The method of claim 13 wherein said solar selective coatingcomprises at least one cermet layer.
 16. The method of claim 13 whereinsaid apparatus is self-supporting.
 17. The method of claim 16 whereinsaid apparatus is capable of near simultaneously converting to heat atleast about 85% of said solar radiation while reradiating less thanabout 15% of said heat while said coating is at a temperature of lessthan about 100° C.
 18. The method of claim 16 wherein said solarselective coating comprises at least one cermet layer.
 19. The method ofclaim 17 wherein said material comprises water and said solar radiationraises the temperature of said water to a temperature at or above atemperature sufficient to disinfect water.
 20. The method of claim 17wherein said solar radiation raises the temperature of said material toa temperature above an ambient temperature.